Be it hanging him out to dry after defeat to Watford in September, or questioning the bravery of a player who fought his way back from a horrific double leg break last season - the England international has felt the brunt of Mourinho’s frustrations at Manchester United.

Perhaps it is a case of tough love from the Special One.

Perhaps it is evidence of a serious breakdown in their relationship.

Either way, it is a situation worth monitoring for Guardiola.

Mourinho has been critical of Shaw

The Catalan inherited four full backs, all over the age of 30, upon his arrival at the Etihad - and immediately intended on addressing both positions.

Arsenal blocked his interest in Hector Bellerin, while Aymeric Laporte - a centre back who can also operate on the left - rejected the chance of a move to City.

If a move for Bellerin was always considered a long shot, it’s unlikely the possibility of luring Shaw ever crossed Guardiola’s mind, given the £31m United paid to lure him away from Southampton.

He was the most expensive teenager in world football when United signed him in 2014 - and inside Old Trafford the belief was that he had the potential to establish himself as one of the finest left backs in Europe.

But when it comes to Mourinho, something just hasn’t clicked.

Shaw has struggled under Mourinho so far

There is now a genuine belief that the 21-year-old could become a high profile casualty of Mourinho’s intended overhaul of the squad he inherited from Louis van Gaal.

There would be no shortage of takers - and it would be little surprise if Guardiola joined the queue.

Shaw’s pace, energy and composure in possession would make him a ideal fit in the system Guardiola is attempting to impliment at City.

He has the youth to meet the demands of Guardiola’s high intensity pressing game, the intelligence and touch to come inside and carry the ball forward central areas.

Just as John Stones has been indulged by the former Barcelona and Bayern Munich manager, Shaw, too, may find a more nurturing environment to develop.

The freedom to make mistakes without the fear of being turned into a scapegoat.

Gerard Pique is a classic case in point.

Pique left United for Barcelona in 2008

A supremely gifted footballer given precious few chances under Sir Alex Ferguson amid doubts about his suitability to the English game.

Given his head by Guardiola, he has established himself as one of the great centre backs of his generation.

In only a matter of months under Guardiola, Raheem Sterling has been transformed from an expensive misfit, to a winger who looks every bit the near-£50m player City signed from Liverpool two summers ago.

If Shaw was hoping for Mourinho to have a similar impact on his game, he has been sorely mistaken.

Guardiola is determined to sign two full backs

If anything, his future has never looked so uncertain.

Guardiola will revisit plans to recruit two full back over the next two transfer windows.

Should Shaw’s situation at United deteriorate further, he may just be on the City manager’s radar.

And here are three more United players Guardiola would get more out of

Daley Blind

As a centre back the Dutchman lacks height, aerial presence and pace.

But his distribution, touch and intelligence make him a classic Guardiola player.

In short, he’s a midfielder, capable of playing at centre back - Guardiola’s dream.

The man who turned Javier Mascherano from a diminutive holding midfielder into a rock at the back would surely find room for Blind.

Blind would be an ideal fit for Guardiola

Michael Carrick

Mourinho may be slowly coming to the realisation that the veteran midfielder is key to getting the best out of Paul Pogba.

His limbs may be ageing, but Carrick’s brain is still among the finest English football has produced over the past decade.